Java RMI Client AccessControlException

Hi I've had some problems trying to get RMI working and was wondering if anyone can help me? I've tried

implementing the client/server code two different ways - one way using a Registry object to bind my remote object

and one using the Naming.rebind()/Naming.lookup() methods (my current code, which I'll supply in a sec).

I noticed when I was using the Registry object to bind the DriverObject I was getting errors about stuff not being

serializable when trying to run the client. Is it talking about the objects that the DriverObject uses?

I'm running all of this on a windows machine using the following commands (the code is located in the folder

C:\pid):
set CLASSPATH= start rmiregistry javac *.java rmic -Djava.security.policy=policy.all javapid.DriverObject java Server java -Djava.security.policy=policy.all -classpath /pid ClientObject

When running the ClientObject I get the following error:
exporter: an exception occurred: access denied (java.net.SocketPermission 127.0.0.1:1099 connect,resolve) java.security.AccessControlException: access denied (java.net.SocketPermission 127.0.0.1:1099 connect,resolve) at java.security.AccessControlContext.checkPermission(Unknown Source) at java.security.AccessController.checkPermission(Unknown Source) at java.lang.SecurityManager.checkPermission(Unknown Source) at java.lang.SecurityManager.checkConnect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.connect(Unknown Source) at java.net.Socket.<init>(Unknown Source) at java.net.Socket.<init>(Unknown Source) at sun.rmi.transport.proxy.RMIDirectSocketFactory.createSocket(Unknown Source) at sun.rmi.transport.proxy.RMIMasterSocketFactory.createSocket(Unknown Source) at sun.rmi.transport.tcp.TCPEndpoint.newSocket(Unknown Source) at sun.rmi.transport.tcp.TCPChannel.createConnection(Unknown Source) at sun.rmi.transport.tcp.TCPChannel.newConnection(Unknown Source) at sun.rmi.server.UnicastRef.newCall(Unknown Source) at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source) at java.rmi.Naming.lookup(Unknown Source) at ClientObject.main(ClientObject.java:405)

I've taken some of the code out of the driver object (the getters/setters are pretty much the same) for this post.

RemoteEvent.java
package javapid; import java.rmi.Remote; import java.rmi.RemoteException; public interface RemoteEvent extends Remote { public double getInput () throws RemoteException; public double getOutput () throws RemoteException; public double getKp () throws RemoteException; public double getKi () throws RemoteException; public double getKd () throws RemoteException; public double getPlant () throws RemoteException; public int getSgm () throws RemoteException; public double getSgmiv () throws RemoteException; public double getSgmav () throws RemoteException; public double getSgni () throws RemoteException; public void setKp (double Kp) throws RemoteException; public void setKi (double Ki) throws RemoteException; public void setKd (double Kd) throws RemoteException; public void setPlant (double g) throws RemoteException; public void setRate (double r) throws RemoteException; public void setSgmiv (double mi) throws RemoteException; public void setSgmav (double ma) throws RemoteException; public void setSgni (double ni) throws RemoteException; public void setSgm (int md) throws RemoteException; public void resetSigGen () throws RemoteException; }

DriverObject.java
package javapid; import java.rmi.*; import java.rmi.server.*; import java.rmi.registry.*; public class DriverObject extends UnicastRemoteObject implements AsyncEvent, RemoteEvent { private int externalCount = 0; private SignalObject SO; private SystemObject SY; private int period = 20; public DriverObject() throws RemoteException { System.out.println("Creating remote control object"); SO = new SignalObject(0.0,5.0,0.01,100,0,0.0); SY = new SystemObject(SO); this.Start(); } public DriverObject(SignalObject Sig, SystemObject Sys) throws RemoteException { System.out.println("Creating remote control object"); SO = Sig; SY = Sys; this.Start(); } public double getInput() throws RemoteException { return SO.getOutput(); } public void setKp(double Kp) throws RemoteException { SY.setKp(Kp); } public void Start() { ClockedEventObject SOT = new ClockedEventObject(period, SO); ClockedEventObject SOY = new ClockedEventObject(period, SY); ClockedEventObject DOT = new ClockedEventObject(period, this); while(true) {} } public void handleAsyncEvent() { // this is used by a clock object I created which is used in the Start() method. // it implements the method defined in the AsyncEvent interface. externalCount++; } public static void main (String args[]) { try { System.setSecurityManager(new RMISecurityManager()); DriverObject Do = new DriverObject (); System.out.println ("Created remote object, now advertising it"); //Registry registry = LocateRegistry.getRegistry ("localhost", 1099); //registry.rebind ("RemotePID", Do); Naming.rebind("RemotePID", Do); System.out.println ("Advertising completed"); } catch (Exception e) { System.out.println ("exporter: an exception occurred: "+ e.getMessage ()); e.printStackTrace (); System.exit (1); } } }

ClientObject.java
import javapid.*; import java.rmi.*; import java.rmi.registry.*; class ClientObject { // public void setRst(int i) { // try // { // System.out.println ("Starting client"); // // Registry registry = LocateRegistry.getRegistry ("localhost", 1099); // Object O = registry.lookup("RemotePID"); // RemoteEvent Rev = (RemoteEvent) O; // // if (i > 0) Rev.resetSigGen(); // } catch (Exception e) { // System.out.println ("exporter: an exception occurred: "+ // e.getMessage ()); // e.printStackTrace (); // System.exit (1); // } // } public static void main(String args[]) { System.setSecurityManager(new RMISecurityManager()); try { System.out.println("Security Manager loaded"); String url = "//localhost/RemotePID"; RemoteEvent Rev = (RemoteEvent) Naming.lookup(url); System.out.println("Got remote object"); System.out.println("Output is:"+ Rev.getOutput()); } catch (Exception e) { System.out.println ("exporter: an exception occurred: "+ e.getMessage ()); e.printStackTrace (); System.exit (1); } } }

Thanks .

The exception that you posted is due to some kind of problem with your security/permissions setup...

Which is strange, because you're including a policy file in your command line when you run the client - any chance that the policy.all file isn't where you think it is? Or that it has some sort of formatting problem?

Is it a "AllPermissions" policy file, or are you configuring specific permissions?

Thanks for the reply Nate, I haven't had a good chance to have a look at the code since friday, but here are a few exta remarks which might help figuring out what the problem is.

I'm not really all that familiar with RMi, so still not exactly sure how to implement it exactly - the tutorial I found online uses the security manager and then at the end almost as a side note says "oh by the way - you can set the policies like this..." (not a quote and grossly reduced - but that's pretty much what I felt about it's coverage). I assumed that policy.all was a default mechanisim for granting all policies to the port (which I figured would be extremely unsecure, but would at-least do for now). How do you setup a policy file to get things working?

The other thing is I'm using localhost -so both server and client classes are being run on the same computer - I THINK that you can get access problems when doing so, but I'm trying to get things working first in an isolated computer right now when I don't have access to a network. I should imagine it should be possible to run both server and client code on the same system if you set things up correctly - but like I said I'm fairly new to this stuff, so I'm stumbling around in the dark a little right now.

I'll try working on it some more and see what I can come up with - more help definetly would be appreciated though...

Cheers

Ok, fixed the security exception problem . Was just a .java.policy problem - now the problem I'm getting is a "java.rmi.NotBoundException: RemotePID" which I find a bit confusing - the RMIRegistry is definetly running and hasn't crashed plus the server object (DriverObject in my case) is running properly (checking my CPU usage it goes from around about 2-5% to 50% - the program is pretty cpu intensive, so the DriverObject definetly is running).

My only conclusions I can come up with are either that the DriverObject isn't advertising itself correctly or the ClientObject isn't finding the advertised object for some reason.

Any ideas people?

I've also tried the alternate way of advertising and connecting to remote objects:

DriverObject
Registry registry = LocateRegistry.getRegistry ("localhost", 1099); registry.rebind ("RemotePID", new DriverObject ());

ClientObjectRegistry registry = LocateRegistry.getRegistry ("localhost", 1099); RemoteEvent Rev = (RemoteEvent) registry.lookup("RemotePID");

It's pretty unsecure, but currently my .java.policy file in the root folder of my user profile looks like:
grant { permission java.security.AllPermission; };

OK - great that you fixed the policy file stuff.

Strange error you are getting now - are you getting the "Advertising completed" message in your server? Are you sure you haven't added some error handling code in the catch() in the server's main() that could "ignore" an error by doing nothing? Since you haven't mentioned codebase yet, and it's the next common problem people usually run into now - I'm wondering if you're really getting an error due to codebase not being set, not succeeding in binding to the registry, and something is causing the error to be "eaten"...

codebase is kind of like classpath, but used for remote programs. If you really have the classpath set to nothing when running rmiregistry, then the initial bind to the registry will throw an exception, because the registry cannot find/load your stub class.

You would do something like this to set the codebase -
javac -classpath . *.java rmic -classpath . javapid.DriverObject set CLASSPATH= start rmiregistry start java -Djava.security.policy=policy.all -Djava.rmi.server.codebase=file:///C:/pid/ javapid.DriverObject java -Djava.security.policy=policy.all ClientObject

Also, in your client - before you do the lookup(), try to do a registry.list() - this returns an array of Strings, and you can print them out to see if the object you're looking for is there, or if there's been a slight misspelling in the name you're looking for.

Thanks for the reply Nathan, yeah, the DriverObject is outputting the expected text when I run it indicating that if there is a problem it's gone unnoticed.

I'll try executing the java files with the flags you mentioned to see if I can get any further that way.

I was thinking about using the client code with some JSP pages I was creating, so I'm not sure how that will go - am I right in thinking that I could use the ClientObject as a javabean seeing as it's simply a load of getters and setters (ok, it has a main method too right now for debugging purposes). Was also thinking about having a java aplet load on a webpage to display a graph.

You know how easy I could do considering I need to setup classpaths and code bases too?

By the way, do I need to load the security manager when I create the remote object the way I mentioned above? the code I've seen before implementing things that way didn't.

Cheers again for your help.

Recompiled the source code after making the change you suggested to the ClientObject - still got problems. Here is a screen dump from both:

DriverObject
Created remote object, now advertising it Creating remote control object

ClientObject
Starting client [Ljava.lang.String;@122cdb6 exporter: an exception occurred: RemotePID java.rmi.NotBoundException: RemotePID at sun.rmi.registry.RegistryImpl.lookup(RegistryImpl.java:106) at sun.rmi.registry.RegistryImpl_Skel.dispatch(Unknown Source) at sun.rmi.server.UnicastServerRef.oldDispatch(UnicastServerRef.java:375 ) at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:240) at sun.rmi.transport.Transport$1.run(Transport.java:153) at java.security.AccessController.doPrivileged(Native Method) at sun.rmi.transport.Transport.serviceCall(Transport.java:149) at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:4 60) at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport .java:701) at java.lang.Thread.run(Thread.java:595) at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(Unknow n Source) at sun.rmi.transport.StreamRemoteCall.executeCall(Unknown Source) at sun.rmi.server.UnicastRef.invoke(Unknown Source) at sun.rmi.registry.RegistryImpl_Stub.lookup(Unknown Source) at ClientObject.main(ClientObject.java:409)

So it looks like the DriverObject is doing what it's supposed to (though technically it might not be advertising right and notflagging that fact). The "[Ljava.lang.String;@122cdb6" outputted by the ClientObject appeared (I think anyways) once I added "System.out.println(registry.list());" right after using the getRegistry() method - is that the problem or is it just println isn't the thing to do here?

Thanks.

You are getting "[Ljava.lang.String;@122cdb6" because it's just printing out the ".toString()" for the array - you need to print the contents of the array - something more like -
String[] list = registry.list(); if (list.length == 0) { System.out.println("No names bound in registry."); } else { System.out.println("Following names bound in registry: "); for (int i = 0; i < list.length; i++) { System.out.println(list[i]); } }

In the output for the server, I noticed that you didn't mention seeing the string "Advertising completed." - this string is printed *after* the actual registry bind in your code above, and the last line you mention is before it. If this is the output from your server - it appears that something is preventing your server from getting to the actual bind - and that the error from the client is correct.

edited -
Found it...
public void Start() { // <--- is called in constructor ClockedEventObject SOT = new ClockedEventObject(period, SO); ClockedEventObject SOY = new ClockedEventObject(period, SY); ClockedEventObject DOT = new ClockedEventObject(period, this); while(true) {} // <--- blocks forever }
[ March 30, 2006: Message edited by: Nathan Pruett ]